Heat fusion-bonding apparatus for electrophotography

ABSTRACT

A heat fusion-bonding apparatus for electrophotography comprising at least one heating element comprising a thin metal sheet housed in an associated container and loosely supported therein by support members each of which is substantially circularly-shaped in section and made of a heat resistant and electrically insulating material so that the heating element can move freely between the support members.

States Patent [19] Aoki et a1.

[11] 3,818,185 [4 June 18, 19 74 1 HEAT FUSION-BONDING APPARATUS FOR ELECTROPHOTOGRAPHY [75] Inventors: Masaharu Aoki, Tokyo; Hiromichi Odajima, Yokohama; Michi Segawa; Ken Ueda, both of Tokyo; Yasushi Eukase, Yokohama; Yasuhiko Teraiima; Hidekazu Yumoto; Takahiko Mizobe, both of Tokyo, all of Japan [73] Assignee: Fuji Xerox Co. Ltd., Tokyo, Japan [22] Filed: Feb. 23, 1973 [21] Appl. No.: 335,152

[52] US. Cl 219/552, 13/25, 219/388, 219/536, 219/548, 338/280, 338/316 [51] Int. Cl. H051) 3/10 [58] Field of Search 219/216, 388, 521, 536, 219/548, 552, 553; 338/217, 280, 316, 318;

[56] References Cited UNITED STATES PATENTS 1,532,017 3/1925 Wry 13/22 X 1,794,310 2/1931 2,162,030 6/1939 2,202,874 6/1940 2,969,448 1/1961 3,036,191 5/1962 Aitken et a1. 338/316 X 3,131,623 5/1964 Seefluth 219/388 X 3,237,142 2/1966 Nuss 338/280 3,373,239 3/1968 Rubisch 13/25 3,420,982 1/1969 Hager, Jr 219/388 3,649,808 3/1972 Garbe 219/216 Primary ExamirierVo1odymyr Y. Mayewsky Attorney, Agent, or Firm-J. T. Martin; Gerald J. Ferguson, Jr.; Joseph J. Baker [57] ABSTRACT A heat fusion-bonding apparatus for electrophotography comprising at least one heating element comprising a thinmetal sheet housed in an associated container and loosely supported therein by support members each of which is substantially circularly-shaped in section and made of a heat resistant and electrically insulating material so that the heating element can move freely between the support members.

1 Claim, 3 Drawing Figures HEAT FUSION-BONDING APPARATUS FOR ELECTROPHOTOGRAPHY CROSS REFERENCE TO RELATED APPLICATIONS Adhesion Device in Electrophotographic Copying Machines, filed by Masaharu Aoki, et al; and Electroconductive Coated, Strip-shaped Heating Unit for Use with Heat F usion-Adhesion Apparatus for Electrophotography filed by Masaharu Aoki, et al, all of the foregoing being hereby incorporated herein by reference.

BACKGROUND or THE INVENTION Field of the Invention This invention relates to a heat fusion-bonding apparatus for electrophotography.

Discussion of the Prior Art In electrophotographic copying machines, it is a common practice to obtain a permanent fixed image by fusion-bonding under heat a paper sheet or the like onto which a toner image on a sensitive medium has been transferred. Various methods are known for effecting such heat fusion-bonding, such as, for example, the methods in which heat conduction or radiation is utilized. In the methods utilizing radiation, the heating element in the heat fusion-bonding apparatus repeats generation and radiation of heat and hence is repetitively elongated and contracted as it generates and radiates heat. Therefore, such heating element must be made of a material that can endure such repetitive elongation and contraction. It is also desirable that such heating element reaches the setting temperature as quick as possible after application of electric power.

SUMMARY OF THE INVENTION The present invention is an attempt to overcome such conventional defects. According to the present invention, there is provided an improved heat fusionbonding apparatus for electrophotography, where: (l) the area of contact between each heating element and the associated supporting members thereof is very small, (2) the heating element is not fixed to its supporting members, and (3) the heating element is supported by only a small number of supporting members,

each of which is made of a material having a small heat capacity.

Other objects and advantages of this invention will become apparent upon reading the appended claims in conjunction with the following detailed description and the attached drawing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an illustrative heat fusion-bonding apparatus in accordance with the present invention.

FIG. 2 is a plane view as taken along the line II-Il of FIG. 1.

FIG. 3 is a sectional view as taken along the line III- III of FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENT In FIG. 1 there is shown an illustrative sketch of a heat fusion-bonding apparatus according to the present invention comprising a pair of containers 1, each arranged in vertically opposed relation. In each container is housed a strip-shaped heating element 2 which is supported therein by being loosely held from both upper and lower sides thereof by supports 3, 3 as shown. Each of said supports 3 is made of a heat resistant and electrically insulating material such as ceramics or quartz glass so as to prevent heat loss. Each support is also preferably a fine cylindricalor rodor thread-like configuration having a substantially circular sectional shape was to minimize friction against the heating element. The supports are positioned at suitable intervals in each of the containers 1, l and may be connected to the sides thereof. It is, of course, possible to form each of the supports 3 from a metal rod coated with a heat resistant and electrically insulating material.

As shown in FIG. 2, the heating element 2 is made from a sheet of metal such as nickel, molybdenum, nichrome alloy or the like and is formed with slits 4 cut horizontally substantially from end to end in an alternate manner to form a plurality of parallel straight strip portions 5, each of said portions 5 being bent centrally along its length as shown in FIG. 3. This arrangement and formation provide high bending strength to the heating element 2 in its longitudinal direction to allow reduction of the number of supports 3 necessitated. Also, since the heating element 2 and its supports 3 are contacted merely pointwise, friction therebetween is sharply diminished.

Thus, the heat fusion-bonding apparatus for electrophotography in accordance with the present invention employs heating elements each of which is made from a thin metal sheet and is housed in a container and loosely supported therein by supporting members which are substantially circular-shaped in section and made of a heat resistant and electrically insulating material, so that each said heating element can freely move between said supporting members and is also able to expand or contract freely according to the heating condition, and hence no trouble is caused in performing heat fusion-bonding operation. Further, since the area of contact between each heating element and its supporting members is small, little heat loss is suffered.

The following is a preferred example embodying the present invention.

EXAMPLE A 50 micron-thick nichrome plate was slitted horizontally substantially from end to end in an alternate manner so as to form a plurality of parallel straight strip portions which were connected endwise to one another, and each of said strip portions was bent centrally along its length, thereby constituting a heating element. This heating element was supported by holding it from its upper and lower sides with fine pipes of quartz glass and then was placed in each of a pair of containers arranged in vertically opposed relation to thereby constitute a heat fusion-bonding apparatus. Then, paper sheets carrying thereon a toner image were passed one after another between the upper and lower heating elements to effect fixing of the images. The power supply was cut off after copying of one sheet and then, after the heating elements cooled to room temperature, power was supplied again to repeat the fixing operation. In this manner, the fixing operations were repeated until 10,000 sheets of copies were obtained. It was found that the heating elements used maintained their initial shape unchanged throughout the entire operation.

Numerous modifications of the invention will become apparent to one of ordinary skill in the art upon reading the foregoing disclosure. During such a reading it will be evident that this invention provides unique 4 v v a heat fusion-bonding apparatus for electrophotography for accomplishing the objects and advantages hereinstated.

What is claimed is:

1. A heat fusion-bonding apparatus for use in electrophotography for heating by radiation a toner image on a copy sheet or the like to thereby fix the image, said apparatus comprising at least one heating element comprising a thin metal sheet slitted zigzag substantially along the length thereof to form a plurality of sub stantially coplanar strips connected endwise to each other in said sheet, said thin metal sheet being substantially parallel to and facing said copy sheet and being housed in an associated container and supported therein and loosely mounted on the top of non-slotted support members each of which is substantially circularly shaped in section and made of a heat resistant and electrically'insulating material so that said heating element can move freely on its said support members, said support members being oriented substantially perpendicular with respect to said strips where the contact between said support members and strip is minimized to thereby minimize heat lost into said-support and optimize the heat capacity of said heating element, each of said strips being folded along the-length thereof to further minimize contact between the sheet and the support members. 

1. A heat fusion-bonding apparatus for use in electrophotography for heating by radiation a toner image on a copy sheet or the like to thereby fix the image, said apparatus comprising at least one heating element comprising a thin metal sheet slitted zigzag substantially along the length thereof to form a plurality of substantially coplanar strips connected endwise to each other in said sheet, said thin metal sheet being substantially parallel to and facing said copy sheet and being housed in an associated container and supported therein and loosely mounted on the top of non-slotted support members each of which is substantially circularly shaped in section and made of a heat resistant and electrically insulating material so that said heating element can move freely on its said support members, said support members being oriented substantially perpendicular with respect to said strips where the contact between said support members and strip is minimized to thereby minimize heat lost into said support and optimize the heat capacity of said heating element, each of said strips being folded along the length thereof to further minimize contact between the sheet and the support members. 